In the semiconductor integrated circuit (IC) industry, technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of IC processing and manufacturing.
Photolithography processes typically form a patterned resist layer for various patterning processes, such as etching or ion implantation. In the photolithography process, a photomask (or mask) is used. The mask includes a substrate and a patterned layer that defines an integrated circuit to be transferred to a semiconductor substrate during the photolithography process. During the formation of the mask or the photolithography process utilizing the mask, various mask contaminants, such as chemical contaminants, are introduced and are hard to remove. The current cleaning methods do not efficiently remove the mask contaminants and may further damage the mask.